Ronald
DePinho, leader of the study and a scientist at Harvard Medical
School, along with a group of Harvard researchers, have regenerated
the bodies of elderly mice turning them into healthy,
rejuvenated animals again.

The
aging process is not completely understood at this point, but what
researchers do know is that free radicals, which are highly reactive
particles created naturally within the body, damage cells which helps
cause the aging process. Other known causes are ultraviolet
light, smoking and
other environmental factors.

But
now, DePinho and his fellow researchers at Harvard Medical School
have discovered that an anti-aging therapy called telomere shortening
has the potential to eliminate age-related issues like dementia and
heart disease by rejuvenating old, worn out organs.

The
body typically contains cells that have 23 pairs of chromosomes, and
at the end of each chromosome is a "protective cap" called
a telomere. Telomeres are cut shorter every time a cell divides,
causing the telomere to eventually stop working, fall into a
suspended state called "senescence" or die. This process
wears out cells and contributes to the aging process.

To
counter this process, DePinho and his team of researchers genetically
manipulated mice, eliminating the enzyme telomerase within them.
Telomerase is an enzyme that prevents telomeres from getting shorter.
In lab tests, these mice aged prematurely and experienced tell-tale
signs of growing older, such as loss of smell, infertility,
smaller brain
size, and damaged organs such as the intestines. But when
given injections to reactivate telomerase, the signs of aging were
reversed and tissues that were previously destroyed had been
repaired.

"What
we saw in these animals was not a slowing down or stabilization of
the aging process. We saw a dramatic reversal - and that was
unexpected," said DePinho. "This could lead to
strategies that enhance the regenerative potential of organs as
individuals age and so increase their quality of life. Whether it
serves to increase longevity is a question we are not yet in a
position to answer."

DePinho
noted that these severely aged mice showed signs of considerable
restoration after only one month of treatment. Among the several
restored organs in the body was the brain, which showed growth of new
neurons.

While
this therapy is ideal for mice, it will be challenging to translate
this type of treatment to humans because slowing the aging process
this way could increase the risk of cancer in humans. Mice have the
ability to create telomerase throughout the span of their lives, but
telomerase eventually discontinues in humans in order to stop cells
from overpopulating and possibly turning into cancerous cells. The
constant production of telomerase in mice kept all of the Harvard
mice from developing cancer after completing treatment.

DePinho
said that increasing the levels of telomerase in humans could
possibly slow the aging process the same way it did in mice, but the
heightened risk of cancer makes this therapy much too chancy for
people yet. But he also pointed out that the treatment could be safe
if it was administered periodically to young
people who do not have living
cancer cells.

"The
goal for human tissue 'rejuvenation' would be to remove senescent
cells, or else compensate for the deleterious effects they have on
tissues and organs," said David Kipling, a researcher at Cardiff
University who studies aging. "Although this is a fascinating
study, it must be remembered that mice are not little men,
particularly with regard to their telomeres, and it remains unclear
whether a similar telomerase reactivation in adult humans would lead
to the removal of senescent cells."

DePinho
and his fellow researchers a Harvard hope to continue working on this
therapy in order to make it accessible to humans without causing
severe side effects, such as cancer. If an appropriate therapy was
created for humans, it could prolong the quality
of life for elderlypeople and
eliminate health problems that come with age such as stroke and
dementia.

"They
key question is what might this mean for human therapies against
age-related diseases?" said Tom Kirkwood, director of the
Institute for Aging and Health at Newcastle
University. "While there is some evidence that telomere
erosion contributes to age-associated human pathology, it is surely
not the only, or even dominant cause as it appears to be in mice
engineered to lack telomerase. Furthermore, there is the ever-present
anxiety that telomerase reactivation is a hallmark of most human
cancers."